Tunneling machine having generator means for liquid jets carried on cutter heads

ABSTRACT

A machine for making tunnels through rock by slitting the tunnel front wall by means of high speed liquid jets which machine comprises a main frame, a carrier movably mounted thereupon, a cutter unit movably mounted on the carrier, whereby the cutter unit is able to cover the tunnel front wall with slots. The cutter unit consists of high speed jet generators which are powered by a non-movable low pressure driving fluid source on the main frame. Impacting devices are provided for breaking down of the remaining parts of the rock intermediate the slots.

United States Patent r191 Taylor et a].

[ TUNNELING MACHINE HAVING GENERATOR MEANS FOR LIQUID JETS CARRIED ONCUTTER HEADS [75] Inventors: Nicholas Simon Hall Taylor,

Saltsjobaden; Hakon Olavi I-lildn; Carl Anders Norn, both ofSaltsjo-Boo, all of Sweden [73] Assignee: Atlas Copco Aktiebolag,Nacka,

Sweden [22] Filed: June 29, 1972 [21] Appl. No.: 266,599

[52] US. Cl 299/59, 239/101, 299/31, 299/62, 299/71, 299/81 [51] Int.Cl. E0lg 3/04 [58] Field of Search 299/17, 60,62, 81, 31, 299/71, 59;239/101, 102; 175/67 [56] References Cited UNITED STATES PATENTS3,326,607 6/1967 Book 299/17 X Mar. 26, 1974 1,284,398 11/1918 McKinlay.I 299/62 X 3,490,696 1/1970 Cooley 239/102 X 3,521,820 7/1970 Cooley239/102 X FOREIGN PATENTS OR APPLICATIONS 151,272 1962 U.S.S.R 299/17176,543 1966 U.S.S.R..... 299/17 Primary Examiner-Ernest R. PurserAttorney, Agent, or Firm-Eric Y. Munson [5 7] ABSTRACT A machine formaking tunnels through rock by slitting the tunnel front wall by meansof high speed liquid jets which machine comprises a main frame, acarrier movably mounted thereupon, a cutter unit movably mounted on thecarrier, whereby the cutter unit is able to cover the tunnel front wallwith slots. The cutter unit consists of high speed jet generators whichare powered by a non-movable low pressure driving fluid source on themain frame. Impacting devices are provided for breaking down of theremaining parts of the rock intermediate the slots.

9 Claims, 11 Drawing Figures PATENIEDmzs m4 SHEET 6 BF 6 TUNNELINGMACHINE HAVING GENERATOR MEANS FOR LIQUID JETS CARRIED ON CUTTER HEADSBACKGROUND OF THE INVENTION This invention relates to a machine formaking tunnels and drifts through rock which machine disinte- Knownmachines of this type disintegrate rock by making slots in the tunnelfront wall by means of mechanical cutters. There are serious problemsinvolved in using such machines partly because of the fact that it is avery hard wear of the cutters and partly because of the fact that verygreat feeding forces are required. These features are disadvantageous bythemselves and have also a limiting effect on the machine power that isappliable to the rock surface.

This invention relates to a tunneling machine by which the abovementioned problems are solved. By a machine according to the inventionthe tunnel front wall is cut into slits or fissures by means of erodinghigh speed liquid jets. In such a machine there is no slitting BRIEFDESCRIPTION OF THE DRAWINGS A machine according to the invention willhereinafter. be described with'refererices to the drawings on which FIG.I is a side elevation of the machine according tothe invention atdrifting of a tunnel. FIG. 2 is a horizontal view of the machine shownin FIG. 1. FIG. 3 is a schematical partly broken side elevation in alarger scale of the machine shown in FIGS. 1 and 2. FIG. 4 shows thefront wall of a tunnel and the working means of the machine according toFIG. 3 and shows schematically how the machine according to FIG. 3 worksthe front wall of a tunnel. FIG. 5 is a partly exploded horizontal viewof the working means of the machine according to FIG. 3 and the frontwall of a tunnel showing the rockdisintegrating principle of thismachine. FIG.

6 is a perspective view'of a cutter head according to an-'otherembodiment of the invention. FIG. 7 shows the same cutter head inanother view which is a cut along line VIIVII in FIG. 6. FIGS. 8 and 9show in two different views another machine according to the invention.FIG. 8 is a side elevation of the machine showing the cutter unit in anerected position. FIG. 9 is a top elevation of the same machine showingthe cutter unit in a horizontal but lateral position. FIG. 10 shows inlarger scale the front part of the machine according to FIG. 9. FIG. 11is a cross section of a tunnel made by the machine according to FIGS.8-10.

SUMMARY OF THE INVENTION The machine shown in FIGS. 1-3 comprises amovable main frame I which is connected to a tail 3 by means of fulcrum2. The tail 3 is guided in a guide box 4 which is arranged to be bracedrelative to the tunnel walls. The bracing of the guide box 4 isaccomplished by extending two hydraulic jacks 5 and 6 into contact withthe tunnel walls. Between the guide box 4 and the main frame 1 there areprovided hydraulic jacks 7 and 8 by means of which steering of themachine in the tunnel is accomplished as well as stepwise feeding of themain frame relative to the guide box 4. i

During the advancement of the machine towards the tunnel front wall theguide box 4 is braced against the tunnel walls by means of the jacks 5and 6 whereupon the main frame 1 is forced forwards by the hydraulicjacks 7 and S. As these jacks have obtained their full length theguiding box is released from the tunnel walls by retracting the jacks 5and 6 whereupon the guide box 4 is pulled forwards by retracting thejacks 7 and 8. Then, the guide box 4 is again braced against the tunnelwalls and another advance movement of the main frame can be performed.

In steering the machine the length of the hydraulic jacks 7 and 8 areadjusted individually so as to make 7 the tail 3 form an angle to themain frame 1. (As indicated in dotted lines.) Then, the tail 3 is lockedin this position relative to main frame by means of a mechanical lockingdevice. (Not shown). Now, the main frame can be advanced along a curvedpath by means of the hydraulic jacks 7 and 8. i

- At the forward end the machine rests in a guide shoe 9 and issupported by adjustable support means 11. By means of the support means11, the machine is kept in level position while the guide box 4 isreleased from the tunnel walls.

Moreover, the machine is equipped with a conveyer 12 and a loadingdevice 13 for collecting and transportation of disintegrated rock.

At the forward end of the main frame 1 there is journalled a carrier 14(see especially FIG. 3) which is rotated by-a motor 15 via a gear 16.Upon the carrier 14 there is rotatably mounted a cutter unit 17 andmounting head 18 for supporting mechanical breaking means. The cutterunit 17- and the mounting head 18 are rotative about axes which areparallei to the rotation axis of the carrier 14 and when rotatedtogether with the carrier they describe planetary movements. The cutterunit 17 and the mounting head 18 are rotated by a common motor 19 via aworm gear 20 and a spur gear 21. The worm gear 20 and the spur gear 21have in common an intermediate wheel 22 which is journalled coaxiallywith the carrier 14. As the motor 19 is stationary the rotation speed ofthe cutter unit 17 and the mounting head 18 relative to the carrier 14is defined by the difference in speed between thecarrier 14 and theintermediate wheel 22.

The cutter unit 17 comprises a high pressure generator consisting of ahousing in which a doubleacting differential piston 23 is reciprocable.The piston 23 consists of two identical high pressure plungers 24a,b andan intermediate wider low pressure part 25. The former work incorresponding high pressure chambers in the housing to which areconnected water supply conduit 26a,b, water outlet conduits 28a,b andjet nozzles 27a,b. The intermediate low pressure part 25 of the piston23 works in adrive chamber 29 to which is connected conduits 3la,b forsupplying and draining of hydraulic fluid. In the high pressure chambersthere is obtained a pressure of about 3,000 to 6,000 atmospheres. Themagnitude of the pressure obtained is due to the pressure of the drivinghydraulic fluid as well as the relationship between the low pressure andhigh pressure areas of the piston 23. j

The high pressure chambers of the high pressure generator arecontinuously supplied with water by a pump 32 through a conduit 33 inthe carrier 14 and check valves 34a,b in the cutter unit 17.. The drivechamber 29 is supplied with hydraulic fluid by a pump 35 through acontrol valve 36 and the conduits 3la,b. The

pump 35 is connected to a hydraulic fluid tank 38 by means of a conduit37 and delivers hydraulic fluid at the pressure of 150-350 atmospheres.The pump 32 delivers water at a pressure of about 30 atmospheres.

The purpose of the control valve 36 is to alternately supply hydraulicfluid to the two sides of the drive chamber 29 for reciprocating of thepiston 33. The control valve 36 is activated by an electric circuitwhich comprises a source of current 39, a contact means 40 and anelectromagnetic coil 41. The contact means is mounted on the carrier 14and is activated by a cam 42 on the cutter unit 17. The control valve 36is shiftable just in one direction by means of the electric circuit andis biased in the other direction by a spring 43. The control valve 36 isshifted by means of the electric coil against the biasing force of thespring 43 as the cam 42 acts upon the contact means 40. In order tosynchronize the reciprocation of the piston 23 relative to the rotationof the cutter unit 17 the cam 42 has to be of such a length that it actsupon the contact means at intervals separated by 180. By such anarrangement water jets are produced under a certain, predetermined angleinterval of the rotation of the cutter unit 17 relative to the carrier14.

Of course, the control valve can be shifted in other ways, for examplehydraulically. The electric control circuit is then exchanged by ahydraulic circuit.

The mounting head 18 carries two impacting devices 44a,b which arelocated in parallel planes and which are directed in angles forwardlytowards the front wall of the tunnel. Each of the impacting devices44a,b consists of a cylinder 50, a hammer piston 45 and an impactingtool 46. The impacting devices 44a,b are actuated by hydraulic fluiddelivered by a pump 47 through a conduit 48 in the carrier and controlvalves 49a,b. The pressure fluid may consist of compressed air orhydraulic oil and the pump 47 is consequently a compressor or ahydraulic pump.

As illustrated in FIGS. 4 and 5, disintegration of rock at this machineis accomplished by cutting cracks or fissures in the tunnel front walland by breaking down of the remaining parts of the rock intermediatesaid cracks by means of the impacting devices 44a,b. As they are beingcut during rotation of the cutter unit 17, the fissures are curved,having one end at the periphery of the tunnel and the other end neartunnel center. The slits are cut by eroding high speed water jets whichare produced by the high pressure generator during a predetermined angleinterval of the rotation of the cutter unit 17 relative to the carrier14. The operating cycle of the piston 23 is for this purposesynchronized to the rotation of the cutter unit 17 relative to thecarrier 14.

' This is accomplished by the cam controlled electric circult includingthe operating valve 36 so that the piston 23 always will make a workstroke within one and the same angle interval. As the high pressuregenerator is double-acting there are out two slots during each round ofthe cutter unit 17.

The operation of the machine is the following,

The guide box 4 is braced against the tunnel walls by the hydraulicjacks 5 and 6 and the tail 3 is adjusted and locked in a predeterminedangle relative to the main frame. Then the latter is pushed forward bymeans of the hydraulic jacks 7 and 8 along a predetermined path.Simultaneously, the carrier 14' is rotated by means of the motor 15 andthe cutter unit 17 and the mounting head 18 are rotated by the motor 19.Now, the high pressure chambers of the high pressure generator aresupplied with water by the pump 32.

The operation of the cutter unit 17 is hereinafter described withreferences to FIGS. 3 and 5.

In the position shown in FIG. 3 the piston 23 has just reached its upperend position and has during its upward stroke produced a water jetthrough the nozzle 27a. In this position the cam 42 acts upon thecontact means 40 so that the control circuit is closed and the coil 41has moved the control valve 36 to open the conduit 31b. Hydraulic fluidis fed from the pump 35 through the conduit 31b into the lower part ofthe drive chamber 29.

By further rotation of the cutter unit 17, the action of the cam 42 uponthe contact means 40 will be interrupted so that the control circuit isbroken and the shifting force of the coil 41 is interrupted. Thus, thebiasing force of the spring 43 will move the control valve 36 to theopposite position wherein hydraulic fluid is conducted to the upper partof the drive chamber 29 through the conduit 31a. Meanwhile, the pump 32has filled the lower high pressure chamber with water, and, as thepiston starts on its downward stroke, the check valve 34b is closed andwater is forced out through the conduit 28b and the jet nozzle 27b at avery high velocity. The water jet thereby obtained has a duration ofalmost half a revolution of the cutter unit rotation or more preciselyuntil the cam 42 ones again acts upon the contact means 40, closing thecontrol circuit and causing shifting of the control valve 36. As thecontrol valve 36 is shifted, the piston 23 changes direction and thecycle is repeated in the opposite high pressure chamber. Yet, the cutterunit 17 has turned half a revolution and a water jet is produced withinthe same angle interval relative to the carrier as the previoussituation.

As the carrier 14 has turned half a revolution, the impacting devices44a,b will be able to break loose the parts of the rock which have beenundermined by the cuts. The parts of the rock which have been brokenloose fall down to the tunnel floor. In order to protect the cutter unit17 from being damaged by the heap of crumbled stones on the tunnelfloor, the carrier 14 is provided with a scrape 51 (see FIGS. 1 and 2).This scraper 51'(see FIGS. 1 and 2) is mounted on the carrier 14 so asto be ahead of the cutter unit 17 as the carrier 14 rotates to shoveaside the stones so that they can be reached by the loading device 13and so that the cutter unit 17 can freely pass.

The relationship between the depth of the slots and the distance betweenthe slots should be at least l-l in order to make it possible for theimpacting devices to break down the remaining parts of the rockintermediate the cuts. That means that the rotation speed of the carrier14 has to be adapted carefully to the depth of the cuts that the waterjets can make, so that the distances between the cuts will not exceedtheir depths.

The advancing speed of the machine must be adapted to the depth of thecuts in the tunnel direction so that the machine is moved forwards adistance equal thereto for each revolution of the carrier 14. Tofacilitate the breaking down of the rock the cut may be made at an anglerelative to the tunnel direction.

The revolution speed of the cutter unit 17 relative to the carrier 14 aswell as the size of the jet nozzles 27a,b

can be varied individually to adjust the cuttingaction of water jet tothe physical properties of the rock being worked.

In the FIGS. 6 and 7 there is shown a cutter unit of a different typefor use in a machine according to the invention. The difference betweenthis cutter unit and the above described cutter unit is that thepreviously described'high pressure generator consisted of adoubl'e-acting pressure implifier of the differential piston type andcutter unit hereinafter described consists of four single-acting highpressure generators 61a,b of a free-piston type for producing highpressure water jets. These jet generators are mounted on a hub 62 andare directed forwards toward the tunnel front wall forming acuteangleswith the rotation axis of the cutter unit. Each of these jetgenerators comprises a housing63, a piston 64, a control valve 65 of thesame type as in the above described machine and the jet nozzle 66. Thepiston 64 has a wider part 67 which works in a drive chamber 68 which issupplied with driving fluid through the control valve 65 forreciprocating the piston 64 in the housing 63. The forward partof thepiston 64 works in a water chamber 69 which communicates with the jetnozzle 66. The water chamber 69 is formed with a high pressure chamber70 at its forward end which communicates directly with the jet nozzle66. The forward part of the piston 64 fits snugly in the high pressurechamber 70. Each of the water jet generators 6la-d are also providedwith a water inlet 71 to which is connected a check valve 72 and anaccumulator 73.

The operating order of the jet generators is as follows,

As in the previously described embodiment, the control valve 65 isshifted by electrical means (or otherwise) during the rotation of thecutter unit so that drivingrfluid will alternately be supplied to thedifferent parts of the drive chamber 68 to make the piston 64reciprocate therein. During a working stroke the piston 64 isaccelerated forwardly whereas the pressure in the water chamber 69rises. Thereby, water flows out from the chamber partly through theinlet 71 and partly through the jet nozzle 66. As the check valve72prevents water from flowing back into the supply conduit and as the sizeof the jet nozzle 66 is very small the main part of the surplus waterwill be forced into the accumulator .73.. This continues until thepiston 64 reaches the high pressure chamber 70, where the latter closesand the water pressure therein rises to a very high level. By reason ofthis high pressure the water is discharged through the jet nozzle 66 ata very high velocity. During the return stroke of the piston, the waterchamber 69 and its high pressure part 70 is filled with water, at firstfrom the accumulator 73 and thereafter, I

when the pressure therein has decreased, water enters through the supplyconduit. Another working stroke may now be initiated. This cycle isrepeated in LOGO-6,000 double-strokes per minute and is characterized bythe short time interval during which the high pressure jet lasts. Thusthe duration of the water jet is short compared to the time period ofthe whole cycle, such as one-tenth thereof. 1

In FIGS. 8-10 there is shown another embodiment of the invention whichcomprises a main frame 101 and a trailing chassis 102. The main framesupports a carrier 103 which is pivotable about a horisontal axle 104.On the carrier 103 there is mounted a cutter unit 105 which consists oftwo high speed water jet generators 106 and 107. These generatorsconsist'of single-acting, differential piston pressure amplifiersprovided with jet nozzles 108 and 109. (The cutter units are notdescribed in detail.)

As distinguished from the previously described embodiment of theinvention, this machine is adapted for production of non-circulartunnels (See FIG. 11). The jet nozzles of the cutter unit of thismachine is movable in substantially horizontal and vertical planes andis intended to cut a number of transverse slits in the tunnel frontwall. As in the previously described embodiment, this machine ispreferably provided with mechanical means for breaking down theremaining parts of the rock which has been undermined by the cuts. Inorder to avoid making the figures indistinct these breaking means areomitted in the drawings.

The main frame 101 rests upon four shoes 110 which are verticallyadjustable by means of hydraulic jacks 111. The main frame 101 is alsoprovided with four horizontally arranged hydraulic jacks 112 by means ofwhich it can be braced against to the tunnel walls.

The main frame 101 and the trailing chassis 102 are interconnected bymeans of two hydraulic cylinders 113 and 114 the purpose of which is toaccomplish the feeding and the steering of the machine. The chassis 102is provided with wheels 115 and horizontal jacks 116 for movement andembracement in the tunnel re spectively. On the trailing chassis 102there are also disposed a hydraulic pump 117, an'electric motor 118 fordriving the pump 117, an oil reservoir 119, a water pump 120 and anelectric motor 121 for driving the pump 120. Moreover, the trailingchassis 102 is provided with a control box 122 comprising control meansfor the machine, an electric hoist block 123 suspended on a rail 124.The chassis also includes an operators platform 126.

Referring to FIG. 10 in particular, the cutter unit arrangement will bemore closely described. The cutter unit 105 is swingably mounted on thecarrier 103 which in turn is pivotable about a horizontal axle 104 whichis perpendicular to the tunnel axis. By pivoting the carrier 103 theforward'ends of the high speed water jet generators are raised orlowered. The swing axisof the cutter unit 105 is perpendicular to thepivot axle of the carrier 103.

For accomplishing of the pivoting movement of the carrier 103 the pivotaxle 104 is revolvable by means of a motor 127 and gear 128. The cutterunit 105 is swingable by means of a hydraulic cylinder 129. Bydraulicpressure fluid for driving the jet generators is supplied to the cutterunit 105 through the pivoting axle 104 of the carrier 103 which, forthat purpose is provided with swivel joints 131 and 132. Thesingleacting pressure amplifiers which constitute the jet generators 106and 107 are inter-connected hydraulically by means of a conduit 133 anda distributing valve 134.

The operation of the machine is following,

The cutter unit 105 is supplied with hydraulic driving fluid from thepump 117 via the swivel 131, the axle 104 of the carrier 103 and the.distributing valve 134. Depending upon the position of the distributingvalve 134, the right jet generator 107 or the left jet generator 106,will be fed withdriving fluid. (The distributing valve 134 is shifted byany suitable means, for instance a hydraulic control circuit.)

In one position, the distributing valve 134 feeds the right jetgenerator 107 as indicated in FIG. 10. The pressure amplifyingdifferential piston of the generator 107 is forced forwards, whereby awater jet is produced through the nozzle 109. Simultaneously, thehydraulic fluid which is situated in front of the low-pressure part ofthe differential piston is pressed out through the conduit 133. Thisconduit is connected to the front side of the differential piston of theleft jet generator 106, whereby the conducted hydraulic fluid causes theleft jet generator to perform a return stroke.

During the return stroke of the left pressure amplifier, hydraulic fluidflows from its rear end and is returned to the reservoir 119 via thevalve 134, the axle 104 and the swivel joint 132.

As a water jet is produced by the right jet generator 107, the cutterunit 105 is swung to the left, whereby a slit is cut from the right handwall of the tunnel to the middle of it. The swinging velocity of thecutter unit 105 is adjusted to the duration of the jet, so that theworking stroke of the jet generator is completed at the same time as theswinging movement is completed.

Now, the distributing valve 134 is shifted, whereby the left jetgenerator 106 makes a working stroke. At the same time the cutter unit105 is swung to the right by means of the cylinder 129 and a slit is cutfrom the left hand wall of the tunnel to the middle of it. A completeslot transverse the tunnel front wall is now cut. The cycle is repeatedafter the jet nozzles 108 and 109 have been raised or lowered bypivoting the carrier 103. Such a pivoting is accomplished by activatingthe motor 127 which turns the pivot axle 124 of the carrier 103 via thegear 128.

As the tunnel front wall is covered with slits and the remaining partsof the rock have been broken down, the machine has to be advanced to anew cutting position. This is accomplished by releasing the chassis 102from the tunnel walls by retraction of the jacks 116 and by retractionof the hydraulic cylinders 113 and 114, whereby the chassis 102 ispulled forwards. When the cylinders 113 and 114 are fully retracted, thechassis is again braced against the tunnel walls by extension of thejacks 116. Thereupon, the bracing jacks 112 of the main frame 101 arereleased and the cylinders 113 and 114 are re-extended, whereby the mainframe 101 is advanced to a new cutting position where it is braced tothe tunnel walls by re-extension of the jacks 112. Now, the machine isready for cutting another series of slits in the tunnel front wall.

Steering of the machine horizontally into curved paths is accomplishedby individual manoeuvring of the cylinders 113 and 1 14 so that the mainframe 101 is disposed at an angle relative to the chassis 102. Thisangle-setting is maintained during the stepwise advancement of themachine.

Vertical steering of the machine is accomplished by manoeuvring of thejacks 1 11. The machine is also prevented from getting into a helicalpath by adjustment of the jacks 111.

The invention is not limited to the described and shown embodiment butcan be freely varied within the scope of the claims.

What we claim is:

1. A tunneling machine, using high velocity fluid jets for making slitsin the tunnel front wall, comprising a main frame movable on the tunnelfloor, a carrier rotatably mounted on said main frame for rotation aboutan axis coaxial with the tunnel axis, a cutter unit engaging saidcarrier for rotation about an axis spaced from and parallel to thetunnel axis, said cutter unit comprising at least one high pressuregenerator connected to a jet nozzle at one end and to a power source atthe other end, said power source being controlled to supply drive powerat predetermined intervals to said generator, a mounting head rotatablyengaging said carrier for rotation about a separate axis spaced from andparallel to the tunnel axis and supporting at least one mechanicalbreaking means for breaking down the undermined portion of the tunnelfront wall between the slits produced by the fluid jets and motor meansfor rotating said carrier and separate motor means common to said cutterunit and said mounting head for moving the same in a planetary pathabout said carrier.

2. A tunneling machine according to claim 1, characterized in that eachhigh pressure jet generator comprises a differential piston typepressure amplifier.

3. A tunneling machine according to claim 2, characterized by onedouble-acting differential piston type pressure amplifier arranged toalternately serve two jet nozzles.

4. A tunneling machine according to claim 1, characterized in that saidhigh pressure jet generator of each cutter head comprises a free-pistontype pressure jet producing device.

5. A tunneling machine, using high velocity fluid jets for making slitsin the tunnel front wall, comprising a main frame movable on the tunnelfloor a power source disposed on said main frame, a carrier pivotablymounted on the main frame for pivoting about a horizontal axisperpendicular to the tunnel axis, two cutter units arranged to swingtogether about an axis perpendicular to the pivot axis of said carrier,each of said two cutter units comprising a high pressure generator and ajet nozzle, said high pressure generator being energized by said powersource to supply active power alternately to said generators.

6. A tunneling machine according to claim 5, characterized in that thecutter units are arranged to cut substantially horizontal slits in thetunnel front wall by swinging relative to the carrier and that one ofthe cutter units covers one half of the front wall, whereas the othercutter unit covers the other half.

7. A tunneling machine according to claim 6, characterized in that thedistance between the jet nozzles are substantially equal to half thetunnel width and that each jet nozzle is arranged to be moved over adistance substantially equal to half the tunnel width only.

8. A tunneling machine according to claim 5, characterized in that saidhigh pressure jet generator of each cutter unit consists of adifferential piston type pressure amplifier.

9. A tunneling machine according to claim 5, characterized in that saidpressure generator of each cutter unit consists of a free-piston typepressure jet producing device.

1. A tunneling machine, using high velocity fluid jets for making slitsin the tunnel front wall, comprising a main frame movable on the tunnelfloor, a carrier rotatably mounted on said main frame for rotation aboutan axis coaxial with the tunnel axis, a cutter unit engaging saidcarrier for rotation about an axis spaced from and parallel to thetunnel axis, said cutter unit comprising at least one high pressuregenerator connected to a jet nozzle at one end and to a power source atthe other end, said power source being controlled to supply drive powerat predetermined intervals to said generator, a mounting head rotatablyengaging said carrier for rotation about a separate axis spaced from andparallel to the tunnel axis and supporting at least one mechanicalbreaking means for breaking down the undermined portion of the tunnelfront wall between the slits produced by the fluid jets and motor meansfor rotating said carrier and separate motor means common to said cutterunit and said mounting head for moving the same in a planetary pathabout said carrier.
 2. A tunneling machine according to claim 1,characterized in that each high pressure jet generator comprises adifferential piston type pressure amplifier.
 3. A tunneling machineaccording to claim 2, characterized by one double-acting differentialpiston type pressure amplifier arranged to alternately serve two jetnozzles.
 4. A tunneling machine according to claim 1, characterized inthat said high pressure jet generator of each cutter head comprises afree-piston type pressure jet producing device.
 5. A tunneling machine,using high velocity fluid jets for making slits in the tunnel frontwall, comprising a main frame movable on the tunnel floor a power sourcedisposed on said main frame, a carrier pivotably mounted on the mainframe for pivoting about a horizontal axis perpendicular to the tunnelaxis, two cutter units arranged to swing together about an axisperpendicular to the pivot axis of said carrier, each of said two cutterunits comprising a high pressure generator and a jet nozzle, said highpressure generator being energized by said power source to supply activepower alternately to said generators.
 6. A tunneling machine accordingto claim 5, characterized in that the cutter units are arranged to cutsubstantially horizontal slits in the tunnel front wall by swingingrelative to the carrier and that one of the cutter units covers one halfof the front wall, whereas the other cutter unit covers the other half.7. A tunneling machine according to claim 6, characterized in that thedistance between the jet nozzles are substantially equal to half thetunnel width and that each jet nozzle is arranged to be moved over adistance substantially equal to half the tunnel width only.
 8. Atunneling machine according to claim 5, characterized in that said highpressure jet generator of each cutter unit consists of a differentialpiston type pressure amplifier.
 9. A tunneling machine according toclaim 5, characterized in that said pressure generator of each cutterunit consists of a free-piston type pressure jet producing device.